Saturday, December 31, 2011

Feliz nuevo año!

Happy New Year!

And thanks for reading. I began this blog in September because after a year of working in various places on interesting things, I was constantly being asked why I didn’t have one. In the first three months, over 1300 visits have been logged from countries all across the world – US has the most visits and, strangely, Russia the second-most! I also added four coauthors – all very, very good naturalists and good friends.  So here’s to another year of interesting natural discoveries for everyone!

Treefrog - 1 cm - Chascomus, Argentina
I’ll recap my year a little bit (since my year revolved around birds/bugs, it is relevant) and show some pictures from it.

I started 2011 in Buenos Aires ushering in the New Years by getting pickpocketed – then it was off to Salt Lake City for the Society of Integrative and Comparative Biology Conference – a hell of a lot of fun and incredibly informative. Then after a couple weeks at home and Cornell (experiencing -18F weather) I set off to erect boxes for the Bahama Swallow on Abaco Island in the Bahamas. Those three weeks were spent chasing birds/building bird boxes with a healthy dose of running on the beach and hanging out with everyone there.

Southern Sea-lion pup, Beagle Channel

Spectacled Tyrant, Chascomus, Argentina

Upland Goose male, Harberton, Argentina

Great Blue Heron, Abaco, Bahamas

La Sagra's Flycatcher, Abaco, Bahamas

Then it was off to Pacora, Peru, a very poor, rural little town in the northern desert. While I had some trials here (illnesses, bribes, severe language barrier), no place in South America has seemed quite as much like home as the Hospedaje Naylamp on calle 28 de Julio (highly recommended). When I was young, a fascination with deserts began (with myself about as removed from a desert as one could ever be) and this was my first time really experiencing a desert. The swallows were small and parched, bright green velvet ants ran their little paths and old dragonfly friends Pantala flavescens and P. hymenaea flew overhead.

Peruvian Meadowlark, Pacora, Peru

Peruvian Thick-knee, Pacora, Peru

After the season ended, a week of travelling with Fernando Angulo (Birdlife International) looking for the Gray-bellied Comet, an endangered hummingbird, in sites where historically it had occurred was fairly unsuccessful – we found it only in the location it was known from – but awesome nonetheless. Then I travelled with my father and sister around the south – Arequipa, Machu Pichu, and Cusco - which was a great end to the trip.

Andean Condor, male, Arequipa, Peru

Giant Humminbird fledgling, Ancash, Peru

Mourning Sierra-Finch, a personal favorite bird, Arequipa, Peru

Vicuna, Arequipa, Peru
Then off to Nantucket to work for the Maria Mitchell Association on insect/bird stuff until September.

Automeris io, Nantucket

Automeris io, Nantucket (changed a bit, aye?)

Barn Owl, which one of the coauthors, Julia Blyth is studying
October brought me to Chiloe, where I still am now…

Remember that skull? Dromiciops gliroides, el monito del monte
Rhionaeschna sp., Chiloe Island

More later!

Friday, December 23, 2011

The Wasp!

You may (or more likely, not) recall that I hypothesized the existence of a blue wasp with orange legs here in Chiloe in this post because I found a very wasp-like beetle that seemed to visually and behaviorally mimic a wasp. A couple days ago, while walking the same path, I found a quite intriguing wasp!


Unfortunately, the strong light blew out the metallic blue wings. To refresh, here is the original beetle:


They were roughly the same size and found in the same habitat (forest edge). Does this prove anything? Absolutely not. It would be pretty hard to "prove" that the beetle is a mimic - perhaps impossible - and thus my assertion is entirely unscientific. But I did imagine the existence of a medium-sized metallic blue wasp with orange legs and sure enough, it showed up!

Friday, December 9, 2011

Another new dragonfly family and basic dragonfly sex

Around the river here there has been a big dragonfly teasing me for awhile now. I spent several hours over the course of a couple weeks trying unsuccessfully to catch it or even just find it perching and see it well. I suspected it was a Neopetalid - a family of only one species: Neopetalia punctata. So yesterday I resolved to catch it and settle the issue - reserving the whole afternoon for the pursuit. Luck was on my side and immediately it flew by me and I netted it - all within 5 minutes. Upon catching it, I realized it was not the species I suspected, but another family entirely: Austropetaliidae - and quite a bit bigger than I initially realized (but still smaller than the Phenes raptor of the last post).

Hypopetalia pestilens, female, Chiloe Island
The family is restricted to only Chile and Australia, surely a remnant of the fact that these two land masses were once (oh so long ago) joined. There are a few other species in Chile, which I may be able to find in the upcoming weeks. It has been much talked about that the butterfly fauna of Chile is severely depauparate compared to similar areas (California is a good comparison in some ways), but it seems like the odonate fauna here is quite diverse. Interestingly, I have found that while butterflies are, by all standards, uncommon here - there are quite a few day-flying moths around, which is rare (but certainly not unknown: Cisseps and Ctenucha come immediately to mind) at home, perhaps using the vacant niches of butterflies as day-flying nectar feeders. I have even watched a few skippers tussling with the moths over territory.

Enough speculation: more pictures of the bug.

Hypopetalia pestilens, female, Chiloe Island

Hypopetalia pestilens, female, Chiloe Island
 How do I know this is a female? Odonates are among the easiest insects to determine sex as adults (orthoptera: crickets, katydids and grasshoppers are also simple). Take a look at the abdomen of the above:


See the little spike sticking out near the bottom of the end of the abdomen? That is the ovipositor, for laying eggs. Males have two sets of specialized sexual organs: claspers on the end of the abdomen for holding the female and on the second abdominal segment a "penis" that functions both to inseminate the female, but also to first remove the sperm of other males so that the maximum number of offspring will belong to him. Coupling of the sexes involves the male grabbing the female behind the head and the female bending her abdomen up to receive sperm, this position is called a mating wheel. Then the male generally oversees the laying of eggs, either by flying tight circles around the female while she lays eggs or by remaining attached, as seen here:

Nehelannia gracilis, male above, female below, Nantucket

Monday, December 5, 2011

More mystery teeth (and the solution)

Because obviously you all are dying to know the solution to the mystery skull (and how on earth you might go about identifying a small mammal skull), I have an in-depth explanation for you. But first, a new tooth (yes, that is a hint to the last solution) mystery. What the hell animal do these come from? When I first found these, in a museum, all I had was a latin name - I was a little puzzled...


There is only one animal like this in the world, so no country information is necessary. I have never seen one alive, though I would certainly like to.

So on to the solution to the other skull. No scale was necessary, though the mosses nearby show that it was a small skull, only a couple centimeters at maximum, which discounts elephant as a possibility. First, are the teeth differentiated? Yep, so it is not a fish, reptile or amphibian - as in those groups all the teeth look the same. Ok, so let's count the teeth (click the picture to blow up). To determine dental formula, you count all teeth on one side of the mouth in each type (incisors, canines, premolars, molars). I see 5 incisors, 1 canine, 3 premolars and 4 molars in this beast. Compare to yourself: 2 incisors, 1 canine, 2 premolars and 3 molars (2 if you have had your wisdom teeth out). Dental formula is important in determining relationships and taxonomic groups.

Now look at the openings on the roof of the mouth (palatal fenestration - literally palate windows). Do you have those? Didn't think so. Now we can conclude that the beast in question is nothing like you - the teeth are different, the skull is structured differently, so what could it be? As I said earlier, it is a mammal, but it is not a group of mammals that most people in the US deal with on a regular basis. There are three main groups of mammals: placentals, marsupials and monotremes. Placental mammals have "normal" pregnancies and comprise most mammalian diversity on earth: us, sheep, cows, mice, capybaras, elk, shrews, hippos, elephants, horses, wolves, whales, etc. Marsupials have pouches, to which very undeveloped babies climb and suckle for months, these include Kangaroos, opossums (the lone marsupial in the USA) and koalas. Monotremes are the whacky mammals, the platypus and the echidna, which lay eggs.

In addition to reproductive strategy, skeletal and dental structure differentiate the groups: placentals have only three incisors, marsupials have up to five, and monotremes have wacky (or no) teeth. Additionally, marsupials have openings in the palate, while placentals do not. Therefore, this photo shows all you need to deduce that the beast in question is a marsupial. A quick google search reveals only two marsupials in Patagonia: Dromiciops (Monito del Monte) and a shrew opossum (Rhyncholestes raphanurus). The opossum has only 4/3 incisors (four upper, three lower), thus this skull must be from Dromiciops).

And what should you know of Dromiciops? Like the Coelocanth, the Tuatara and several other taxa, it is what we call a "living fossil". The last surviving member of a once diverse and widespread (in Australia and Antarctica, back when it was not at the south pole) group, the microbiotheria, it survives only in Chilean and Argentine forests. Not only is it the only remaining species of its genus and family, it is the only one left of its order (compare: our order is the primates, all prosimians [lemurs, et al.] monkeys and apes - thus it would be like just one monkey species is left). Its closest relatives are known from fossils in Australia and Antarctica.

It is a nocturnal omnivore, eating fruit as well as insects and small vertebrates, one each of the wren and rayadito nests here were eaten by Dromiciops, and I occasionally happen upon them in the boxes sleeping for the day. However, they scamper away very quickly, and thus I have not gotten a picture yet, but for good ones, see here: http://www.discoverlife.org/mp/20q?search=Dromiciops+gliroides.

Sunday, December 4, 2011

Beetles aplenty (Ceroglossus)

Right under just about everyones' noses are loads of pretty and interesting beetles just waiting to be found (and photographed). Many of the coolest are members of the family Carabidae, the ground-beetles, into which the family Cicindelidae, the tiger beetles, has been absorbed. But since I have written a bit about the tiger beetles (see here) on to other carabids!

Ceroglossus sp., Chiloe Island, Dec 3, 2011
Ground beetles are a rather diverse family with herbivorous, carnivorous and omnivorous members, but we'll focus on the carnivores here, as many of them are big and flashy. As I said earlier, they are common and widespread, but rarely seen. In eastern North America we have a few genera of flashy beetles - Calosoma scrutator being the most widespread large flashy species, see here for pictures. That and others, including the Callisthenes calidus pictured below are caterpillar hunters. While most ground beetles stay are true to their name, these species often climb trees in search of prey - however, they can still move quite rapidly on the ground, I have read that some carabids are among the fastest animals for their size with long thin legs well suited to the purpose.

Callisthenes calidus, Nantucket, MA
These species, being big, juicy beetles, are commonly targeted by birds and mammals and thus have evolved an interesting defensive strategy. They emit a really foul-smelling (and tasting) fluid which causes them immediately to be spat out (theoretically). I can atest, having once accidently gotten a small carabid in my mouth while biking - the resulting taste was the longest-lasting, and most disgusting thing I have ever tasted. But some species still eat them; a scientist here told me that a Chucao followed them on their pitfall lines and would eat the Ceroglossus that they released. 

Ceroglossus sp. (magellanicus?), Nov, 2011
The Ceroglossus are much loved here and one of the symbols of the native forests (which they don't necessarily need - they exist in Eucalyptus groves as well) along with the Monito, the Rayadito and the Pudu. I catch most of them walking along paths as they try to run out of sight, but I was amazed that in one of my small pitfalls here to catch 3 (of the first species) in one night. 

Notice the little hairs (setae) in a row along the inside edge of the wing
covers (elytra). 
When I searched for more info, I was able to find one site (here) entirely devoted to the genus (which is entirely South American), which seemed to be a good resource, but it was in French. Therefore, I was not able to properly ID the species I caught.





Friday, December 2, 2011

A Tern Mystery

While I know there is one mystery still outstanding (the skull, see a few posts below) here is another which I have no answer to.

Black-necked Swans and Hudsonian Godwits (over 1000)

I was out at la Bahia de Caulin, an awesome shorebird (and oyster) spot, poking around for birds when I noticed an immature tern roosting with the gulls. Immature terns can be quite interesting cases for identification and though I suspected this was a South American Tern, I got closer to make sure. I was right, but as I neared, I realized that something else was very interesting about this bird.

Immature South American Tern

That's right, it had only one wing. The mud in the picture actually was not on the bird until I tried to pick it up, at which point it turned on its back and tried to swat me with its legs and its one wing and bite me. Had I been looking at the other side of the tern, I would have walked right by as if nothing was wrong. There was no blood at the wound (though the bone was sticking out), nor was the tern acting odd. It was in the middle of a muddy seashore with nothing for hundreds of meters in any direction. How did it get there (I guess it must have walked)? Where was its wing? What took just its wing? Why was there no blood?

Note the bone just up and to the left of the first joint of my thumb

My guess is that it got tangled in a fishing/seaweed net and somehow lost its wing getting out, but that is just a guess based on how much fishing/seaweed collecting (passively using nets) goes on in this bay. Maybe, as it is an immature, the parents were still feeding it and that is why it was in such good shape. But that is all hypothetical, the truth is I have no idea why this one-winged tern was in apparent good condition on the beach today, and don't expect ever to know.

A two-winged adult, Ushuaia harbor, Dec 2010. 

Ouch.

Thursday, December 1, 2011

Rayadito Banding/Furnariidae

Thorn-tailed Rayadito, almost fledged

The head investigator here in Chile for the swallows also studies another bird, the Thorn-tailed Rayadito. He has sites all over the country and a couple of them are here on Chiloe. However, he and his two students cannot monitor all of the sites, so I have inherited a few duties at two of them, namely banding, measuring and taking blood samples from all the nestlings. And since there is one swallow nest at the site here (plus one Rayadito, two Plain-mantled Tit-spinetail, and seven House Wren – which we don’t gather data on), I have plenty of time to do the rayaditos. Worldwide, there are only two Rayadito species, the other confined to the Juan Fernandex Islands, far off the coast of Chile.

A nest waiting to be banded - the green feathers are from
Slender-billed Parakeets, a rare Chilean parrot.

Today was the third time to Caulin, a beautiful little village that makes its living collecting seaweed out of the bay and has almost 100 nest boxes set up on a sanctuary (Fundo de los Cisnes – Foundation of the Swans). I ventured out alone this time to locate the last twenty boxes and band whatever babies were in them.
Banding consists of putting a permanent metal ring with a number on it around the bird’s leg, which will remain forever. Scientists and interested amateurs have been doing this for the better part of a century and many, many big discoveries have come out of it, such as migration routes, wintering grounds and site fidelity as well as being able to recognize individual birds in scientific studies of behavior, ecology and evolution. Rayaditos are a tiny little bird, so I use a tiny little band. The Barn Owls that are banded every year on Nantucket (and which a friend is now doing a cool project on) require massive bands with a foldable flange on them so the owls don’t tear them off. But the Rayaditos present no such problems.

Set up workspace, bands, pliers, needles, cotton, capillary tubes, blood paper,
calipers, pesola and vaseline (to move away from vein).
Secondly, I measure various parts of the body – bill, tarsus, wing and tail length plus mass – but because these measurements are not done at a uniform time (i.e. some of the babies might be 12 days old, others 9), I don’t know how much value these measurements are going to be. Then I take a little bit of blood from the brachial vein by pricking it with a needle as it crosses the bird’s shoulder joint – extracting the small drop of blood with a capillary tube. Usually a few seconds of pressure with a piece of cotton stops this – I have never had to use styptic powder (yet). Then the blood is transferred to a storage medium. For swallows, we use a DNA lysis buffer, which breaks up the cells and preserves the DNA, while for the Rayaditos we use a special blotting paper which preserves it.

Adult Rayadito, concerned about its babies.
Then quickly and quietly, I put the babies back in the nest and let the parents have them back. Usually during the entire ordeal, the parents are no more than a foot or two from me, screaming (wouldn’t you be?) and carrying on. A few have even learned to pull leaves off the tree and drop them in my general area, which is both ingenious and entirely ineffective.

They start being obnoxious young.

Rayaditos belong to an interesting family of birds: the furnariids, otherwise known as the ovenbirds. They are of very distant relation to the Ovenbird of North America (a wood-warbler), but are a common group in South America. They get their name from the nest of a few species which looks like a dutch oven (also where the other Ovenbird gets its name) though the majority build stick nests. They take a variety of niches here, the rayadito and tit-spinetails are very chickadee-like, treerunners are like nuthatches,  the hornero is similar to a robin/catbird, rushbirds are like marsh wrens and others are quite unlike anything we have here…

A woodcreeper (Red-billed Scythebill). Evolution is weird. 

The Rufous Hornero (pictured above) is the national bird of Argentina and a conspicuous bird in the entire northern part of the country. It is probably from this bird's nest that the family derives its name, as the nest is a carefully constructed mud "oven" - and the name of the bird is a derivative of the spanish word for oven, horno. 


Rufous Hornero nest (nido), Chascomus, Argentina, 2010


A thornbird - pale-breasted, freckle-breasted or greater? Santa Fe, Argentina

Sunday, November 27, 2011

Egg Shape

Why do birds’ eggs (or any eggs, for that matter) vary in shape?

At least one very intuitive shape exists. Murres, an alcid (the same family as puffins), lay very pointed eggs that roll in circles, which is important as to avoid the eggs rolling off the small ledges on cliffs that they lay the eggs on, without the protection of a nest.  But most birds build nests and avoid that problem.

Rock cormorants, not murres, but the same nesting situation
Important to all eggs is the amount of surface area/volume – a ratio that you may remember from cells, but is important at all levels of biology. Insects are limited in size by this ratio – that is why a walking stick might be 6” long, but no insect is 6” wide. Bird eggs, like everything living, respire and the eggshell, though it might seem solid, is actually somewhat permeable and while an egg needs to exchange gasses, it does not want to lose too much water – as it is laid with all the water it needs, but very little extra. Scientists have predicted that, if this is the only important factor, all eggs should be round as this is the lowest SA:V. Add to this that round eggs are the strongest and you might think all eggs would be round. But they aren't.
Eared Dove nest, Chascomus, Argentina

The shape seems influenced by the female reproductive tract of the particular bird, and this probably accounts for egg shape variation between species. But bear in mind this is a proximate cause – i.e. the egg shape is determined by this, but ultimately, the shape given is the result of evolution of the reproductive tract. But then why do eggs differ perceptively in shape between members of the same species, or even more puzzlingly, between the same female?

 

These three eggs are all of Tachycineta stolzmanni, the Tumbes Swallow, lit to illuminate yolk area. 

An interesting idea has been floating around since the 1940’s. Shape might have to do with how effectively eggs can fit under the incubating bird. Most female birds (and some males) possess a “brood patch” (or several), an area of skin with very good blood supply which, during the breeding season, is featherless and used to heat the eggs. Perhaps the best shape of eggs is one that the most eggs can fit under the brood patch. This model, most recently simulated by Barta and Szekely in 1997, predicts differently shaped eggs for different numbers of eggs and shapes of brood patches. Their predictions are somewhat borne out by observational data – birds that lay one, or many, eggs generally have rounder eggs and ones that have four eggs generally fit together very tightly with their tips pointed in.

Penguins are one of the only groups of birds without a brood patch,
they have a pouch formed by the skin.

But look at any dozen eggs you get from a grocery store and you can see an exception to this. These are all different shapes and chickens are indeterminate layers, meaning that they can lay many eggs (and the number is not known to the chicken when she begins, thus how does she compensate for shape?), and if you keep taking eggs from a chicken, the chicken keeps laying them. And yet shape differences persist in the species. A study of Blackbirds and Great Tits in Spain showed that shape and clutch size were independent, another thorn in the side of this prediction.


Rufous-collared Sparrow and nest
Perhaps small differences in shape have no functional difference and thus selection wouldn’t operate on them. An entirely plausible, and possible, solution and perhaps a really pointed or perfectly round egg might be disadvantageous, but all the variation between two points is similar. But before deciding this, bear in mind the Grant’s finches (dealt with wonderfully in Jonathan Weiner’s book The Beak of the Finch), where a millimeter of beak difference, barely perceptible to an observer, meant life or death for the finches. It seems likely that some other force, or some combination of the discussed forces, determines the shape of a bird’s egg.